1. Field of the Invention
The present invention relates to a remaining amount detection sensor for detecting a remaining amount of content of a container, and an ink-jet printer using the same.
2. Description of the Related Art
Up to now, there have been known various remaining amount detection sensors for detecting a remaining amount of content, such as liquid and powder, contained in a container.
For example, in an ink-jet printer for performing image recording and the like by discharging ink from an ink-jet head, a remaining amount of ink contained in an ink tank for supplying ink to the ink-jet head is monitored. Then, when the ink remaining amount decreases, ink is replenished from an ink replenishment tank, and in a case where the ink tank is a replaceable cartridge, it is notified that a time for replacement of the ink tank approaches. Further, there has been known that a remaining amount detection sensor of a capacitance type is disposed outside the ink tank, thereby detecting the ink remaining amount.
For example, JP 08-197749A discloses an ink-jet printer which includes an ink tank for storing conductive ink, electrodes for outside of the container, and the two detection electrodes sandwiching the container are affected by other conductive structures and electrical circuits disposed on the periphery of the detection circuit, so there arises a problem in that the capacitance is changed due to a change in surrounding environments and the like, and a measurement error or erroneous detection occurs.
In particular, in the case of the ink-jet printer, the change in capacitance of the ink tank due to the change in remaining amount of the ink to be detected is generally extremely small. Accordingly, the noise due to the external factors has a large effect on the measurement accuracy.
Further, in many cases, the ink tank of the ink-jet printer is disposed near the electrical circuit for controlling discharge of the ink-jet head and controlling a movement mechanism and the like of the ink-jet head, is movably held on a recording medium, and is disposed near a movable member. As a result, an amount of noise to be generated due to the external factors is increased.
In addition, in the ink-jet printer, ink tanks for each color are prepared for color recording, and the ink tanks are arranged in parallel with each other. As a result, detection electrodes for the ink tanks for different colors are adjacent to each other. For this reason, the capacitance is formed also between detection electrodes of another adjacent remaining amount detection sensor, which causes an increase in measurement error.
In order to eliminate the effects of the surrounding environments, the remaining amount detection sensor and the ink tanks can be disposed to be spaced apart from other members and other remaining amount detection sensors which affect the capacitance, but there arises another problem in that the apparatus is increased in size.